Transcatheter aortic valve implantation: a revolution in the therapy of elderly and high-risk patients with severe aortic stenosis

Aortography Keypoint Tracking for Transcatheter Aortic Valve Implantation Based on Multi-Task Learning

Currently, transcatheter aortic valve implantation (TAVI) represents the most efficient treatment option for patients with aortic stenosis, yet its clinical outcomes largely depend on the accuracy of valve positioning that is frequently complicated when routine imaging modalities are applied. Therefore, existing limitations of perioperative imaging underscore the need for the development of novel visual assistance systems enabling accurate procedures. In this paper, we propose an original multi-task learning-based algorithm for tracking the location of anatomical landmarks and labeling critical keypoints on both aortic valve and delivery system during TAVI. In order to optimize the speed and precision of labeling, we designed nine neural networks and then tested them to predict 11 keypoints of interest. These models were based on a variety of neural network architectures, namely MobileNet V2, ResNet V2, Inception V3, Inception ResNet V2 and EfficientNet B5. During training and validation, ResNet V2 and MobileNet V2 architectures showed the best prediction accuracy/time ratio, predicting keypoint labels and coordinates with 97/96% accuracy and 4.7/5.6% mean absolute error, respectively. Our study provides evidence that neural networks with these architectures are capable to perform real-time predictions of aortic valve and delivery system location, thereby contributing to the proper valve positioning during TAVI.

The value of screening for cognition, depression, and frailty in patients referred for TAVI

Background: Current surgical risk assessment tools fall short of appreciating geriatric risk factors including cognitive deficits, depressive, and frailty symptoms that may worsen outcomes post-transcatheter aortic valve implantation (TAVI). This study hypothesized that a screening tool, SMARTIE, would improve detection of these risks pre-TAVI, and thus be predictive of postoperative delirium (POD) and 30-day mortality post-TAVI. Design: Prospective observational cohort study, using a historical cohort for comparison. Participants: A total of 234 patients (age: 82.2±6.7 years, 59.4% male) were included. Half were screened using SMARTIE. Methods: The SMARTIE cohort was assessed for cognitive deficits and depressive symptoms using the Mini-Cog test and PHQ-2, respectively. Measures of frailty included activities of daily living inventory, the Timed Up and Go test and grip strength. For the pre-SMARTIE cohort, we extracted cognitive deficits, depression and frailty symptoms from clinic charts. The incidence of POD and 30-day mortality were recorded. Bivariate chi-square analysis or t-tests were used to report associations between SMARTIE and pre-SMARTIE groups. Multivariable logistic regression models were employed to identify independent predictors of POD and 30-day mortality. Results: More patients were identified with cognitive deficits (χ2=11.73, p=0.001), depressive symptoms (χ2=8.15, p=0.004), and physical frailty (χ2=5.73, p=0.017) using SMARTIE. Cognitive deficits were an independent predictor of POD (OR: 8.4, p<0.01) and 30-day mortality (OR: 4.04, p=0.03). Conclusion: This study emphasized the value of screening for geriatric risk factors prior to TAVI by demonstrating that screening increased identification of at-risk patients. It also confirmed findings that cognitive deficits are predictive of POD and mortality following TAVI.

Nanostim-leadless pacemaker

Nanostim™ (St. Jude Medical Inc., Saint Paul, MN, USA; now Abbott Medical Inc. Abbott Park, IL, USA) was the first self-contained intracardiac pacemaker to be implanted in a human patient. A total of 1423 Nanostim devices were implanted worldwide between 2013 and 2016 and three clinical trials were initiated. Although the device was recalled in 2016 owing to rare but serious battery failures, the concept of leadless pacing has gained widespread acceptance and is expanding beyond the initial single-chamber devices to dual-chamber systems, biventricular pacing, and combinations with defibrillators. This review describes the design, results from initial clinical trials, and long-term experiences with Nanostim. It discusses the lessons learned from the pioneering device's successes and shortcomings, many of which are valid for leadless pacemakers in general. This article also considers the Nanostim experience in comparison with the early years of clinical use for other pioneering device therapies. Important questions include how to minimize the risk for short-term complications by appropriate operator training and evaluation of suitable patients, what the long-term performance tells us about safety, as well as the necessity and feasibility of device explantation.